With endless construction and an increasing number of speed-limited sections, is the autobahn still all it's cracked up to be? Well, yes and no.

Imagine how much better your life would be if 150 mph were legal. Commuting times would be slashed—especially if you also fantasize that there’s no traffic—and road trips to Disney World would be so short that you’d have to listen to the Frozen soundtrack only three or four times each way. You’d spend thousands more on fuel but save hours every week and days every year. Time, the man said, is the only irreplaceable commodity.

Then there’s the visceral joy of speed itself, that sensation of running rather than walking, of being very productive, of getting it the hell done. You’d get to experience the true potential of a modern car, rather than the scant percentage of its talent allowed by a 70-mph limit. And don’t forget the thrill of fear, that adrenaline spike as you pass somebody west of Chattanooga at double their speed.

We’re here in Deutschland to find out how life at 150 mph is lived. Germany remains the world’s only sizeable, developed country not to impose speed limits on most of its highway network, a.k.a. the autobahn. Consequently, Germany’s big roads have assumed almost ­legendary status for gearheads everywhere. But is it really the flat-out-driving Valhalla you probably dream it to be? Or, as with German humor and pornography, is it far less satisfying than promised? Does the reality match the fantasy?

This is what 192 mph looks like.

We’re going to answer that question by doing a lap of Germany via autobahn. Starting in Frankfurt, we’ll head to Munich, then on to Berlin, and then back to the big F. Because time is precious, we’ve given ourselves three days to do it and a Mercedes-Benz S63 AMG 4MATIC to do it in—crucially, one with the upgraded 300-km/h (186-mph) speed limiter. You want us to be comfortable, don’t you?

About one-third of the 8000-mile autobahn network now carries either a permanent or temporary speed restriction, but we don’t have to go far to find our first bit of unrestricted highway. Two minutes after leaving the Frankfurt airport, we’re on the A5 headed south. The S63 hasn’t even warmed its fluids before we pass our first Ende aller Streckenverbote (or “end all restrictions”) sign, which, after due consideration and discussion by what must have been umpteen different German technical committees, is a white circle with five diagonal stripes that looks like a symbol for burnouts.

There’s plenty of traffic, but it’s moving quickly and with the relentless lane discipline we’ll soon grow used to. Unlike in America, where drivers disperse all over the road according to the laws of molecular diffusion, German cars stay to the right whenever they aren’t passing. Germany thus seems to move more volume swiftly on a four-lane road than America can with ten lanes.

The S-class settles into a 100-mph cruise over impeccably smooth blacktop, yet we’re still being overtaken by a stream of faster cars. No 911 GT3s with pink wheels—a not-uncommon sight in Germany—but a Volvo V70 complete with both a roof box and two small children in the back, loping down the outside lane at an easy buck-twenty. We travel only 10 miles to our first stop, the Parkplatz Rosemeyer, a small rest area next to the autobahn. These days, used condoms in trees bespeak its popularity as a hookup area. But a stone monument and a modest wooden marker denote the place where Grand Prix driver Bernd Rosemeyer died in 1938, an early victim to Germany’s national obsession with speed. And yes, although we’re not supposed to talk about the war, this is where the Nazis enter the story.

Autobahn historians exist, and they are predictably keen to point out that the earliest German high-speed highways predated Hitler’s rise. Which they did. But it was the Nazi regime that put them on the map, both literally and figuratively. This stretch of A5 between Frankfurt and Darmstadt was the first piece of what was meant to be a vast Reichsautobahnen network across the Third Reich. It opened in 1935 and later was used by Auto Union and Mercedes-Benz for land-speed-record attempts, leading to Rosemeyer’s fatal crash.

Rosemeyer, like all successful German racers of the period, was a member of the Nationalsozialistisches Kraftfahrkorps—basically the Nazi motor club. He was also an honorary member of the SS. Although those who knew him insisted he wasn’t in any way political, he can have been in no doubt, when ordered to Frankfurt in January 1938, that he was driving for the glory of the Fatherland as much as that of Auto Union.